1. Field of the Invention
This invention relates to a quick connector, particularly to one easy to operate for separating a plastic tube processed, with the outer surface of the plastic tube not scarred or hurt.
2. Description of the Prior Art
A first conventional quick connector shown in FIG. 1, for connecting plastic tubes used for RO percolating devices, includes a body 1, and a constricting set 2.
The body 1 has a central through hole 10 for receiving a plastic tube that is used for liquid to flow through.
The constricting set 2 is deposited in the central through hole 10 of the body 1, provided with a constrictor 20 having a center hole for a plastic tube to pass through, an inlet 200 of a large diameter and an exit 202 of a small diameter. The inlet 200 has a plurality of petals 202 spaced apart equidistantly on its annular wall, and the exit 201 also has a plurality of petals spaced apart equidistantly on its annular wall. The dimensions of the petals 202 is larger than that of the petals 203 that are a little sloped inward so as to constrict the surface of a plastic tube to be connected. Further, a press button 22 is provided for pushing open the petals 202 of the inlet 200 for connecting or disconnecting a tube. Further, a bushing 21 is provided to fit in the central through hole 10 and then welded together with the body by means of high frequency processing for preventing the constrictor from loosing out. The bushing 21 is provided with a central cone-shaped hole 210 for the press button 22 to sit therein. The press button 22 has a conical circumference 220 in the lower portion, and a cylindrical circumference 221 on the conical circumference 220 with a connecting edge 222 formed between the cylindrical and the conical circumference 220 and 221. Therefore, when the compress button 22 is forced to fit in the hole 210, the connecting edge 222 is stopped by a front circumference of the bushing 21 to let the compress button 22 stabilized in place. Further, the compress button 22 has a large flange 223 at the upper end to locate at an outer side of the body 1 so as to easily press the compress button 22, and a central through hole 224 for a plastic tube to fit in.
However, this first conventional connector has the constrictor 2 made of metal, resulting in high cost, and their components are rather complicated, having a large dimensions not profitable, in addition to a flaw of potentially hurting the surface of a plastic tube connected. Further, replacing a tube is not convenient, often forced to press tightly the compress button, very inconvenient in operation.
A second conventional quick connector shown in FIGS. 2, 3 and 4 includes a body 3A and a constrictor 3. The body 3 has a tapered central hole 3A0, and a constrictor hole 3A1 formed in an upper portion of the body 3A on the tapered central hole 3A0 with an annular straight vertical wall for an O-shaped ring 3A2 and then the constrictor 3 to fit therein. The constrictor 3 is made integral, having a large circumference 30 and plural petals 31 formed at the circumference 30 in order to constrict a plastic tube 11. Further, the constrictor 3 is provided with an engage member 32 made of metal.
However, the second conventional connector has the following disadvantages.                1. The metal engage member 32 has to be placed in a mold before the constrictor 3 is formed by means of injecting molding process, taking much time and costing much.        2. The metal engage member 32 has to be combined perfectly, or resulting in unqualified products.        3. The metal engage member 32 clamps a plastic tube as shown in FIG. 2, and although four petals 31 push against the surface of the plastic tube 11, actually only four points contact the tube surface, so the tube is easily pulled out by a little force, and if worse, the constrictor 3 may be pulled out together with the tube.        4. The metal engage member easily sticks into a plastic tube, so the tube becomes difficult to be pulled out as shown in FIG. 4, resulting in impossible reuse of the plastic tube, in addition to leaking of liquid.        5. If the constrictor catches a plastic tube for long, without any pulling off, the engage member 32 has bit in the plastic tube, letting the tube impossible to be pulled out.        6. After the engage member clamps tightly a plastic tube, even if the constrictor is pushed inward, forcing the O-shaped ring 3A2 to disfigure, the plastic tube cannot quickly be pulled out.        7. As shown in FIG. 4, in operation, one hand has to press the constrictor, and the other hand has to pull the plastic tube, needing much force, not easily pulling out the tube.        
Next, a quick connector disclosed in a US patent of U.S. Pat. No. 5,230,539 includes a body 11, a sleeve 30 at one side of the body 11, as shown in FIGS. 1-6. If the body 11 is combined with the sleeve 30 by means of high frequency or supersonic process, it is the same structure as the first conventional quick connector mentioned above. As shown in FIG. 3, a collect 40 is provided with an intermediate boss portion 42 and a frusto-conical outer surface 45, which pushes an O-shaped ring 50. The frusto-conical surface is provided with teeth 46 in an inner surface, and the teeth 46 clamp the surface of a plastic tube 60. The flaw of this connector is that the plastic tube 60 can only be stabilized by the frusto-conical outer surface 45, by the teeth 46 clamping the surface of the plastic tube 60. So replacing a plastic tube is very troublesome.